This invention relates to a fluid line detachable coupling for uncoupling and shutting flow of the fluid through the line when a tensile force above a predetermined limit is applied to the coupling in substantially any direction, and more particularly to a coupling for mounting in a fuel supply line of a fuel dispensing station for communicating a first fuel conduit rotatable about a first axis at one end of the coupling to a flexible fuel conduit attached to a second end of the coupling, the coupling having detachable means intermediate the first and second ends permitting uncoupling to shut flow communication at the coupling when the tensile load in the flexible conduit is above a predetermined level irrespective of the direction of the load relative to the first end, i.e., the coupling disconnects when an excessive external tensile load is applied through the flexible conduit at the second end.
It is known in the fuel dispensing art to include a swivel connector at the dispenser/hose interface so that twisting loads applied to the dispenser are not transmitted to the hose resulting in twisting thereof. Such swivels merely permit the dispenser, such as a fuel dispensing nozzle, to be pivoted about one or more axes relative to the axis of the hose, the swivel permitting flow communication between the hose and the dispensing device.
Additionally, it is known to utilize quick disconnect or breakaway couplings in the fuel line spaced from the dispenser so that if a vehicle is driven away from the fuel dispensing station before the dispensing nozzle is removed from the filler neck of the vehicle, an uncoupling will result, shutting the flow of fuel and preventing the volatile fuel to be spilled due to either a dislodging of the moorings of the fuel dispensing station, breakage of the hose, or other failure of the fuel dispensing system. The prior art has proposed a number of decouplers which are actuated by a tensile force in the line.
In U.S. Pat. No. 4,779,638 of Nitzberg et al, the problems and deficiencies of the prior art decoupler units were described including that of premature uncoupling, snap decoupling, and the cumulative affect of tensile force on the line and the hydrostatic forces of the liquid within the coupling, and combination swivel-joint and quick-disconnect coupling devices are disclosed that substantially overcome these problems. The devices there have coupling means between first and second body members which swivel relatively to one another and the coupling means normally acts to connect the body members in flow communication and to decouple when an external tensile force above a predetermined level is applied to the fuel line, and include valving acting for shutting flow communication when the body members are decoupled.
There are, however, certain occasions when the direction of the external tensile force applied to the fuel line is such that both in conventional swivel connectors and in the combination swivel-joint quick-disconnect couplings or connectors disclosed in the aforesaid U.S. Patent where the tensile force will not permit the swivel-joint to pivot, i.e., the reaction force to the external tensile force does not act in a direction which effects rotation about the pivot axis. Such conditions may occur when a swivel-joint having one end connected to a flexible fuel conduit, such as a hose, and the other end connected to a rigid fluid conduit, such as a nozzle or rigidly mounted piping, does not permit the end connected to the flexible conduit to align itself with the direction in which the tensile force is applied. When this occurs a bending moment results which may act to shear the interconnecting members of the joint. For example, if the external tensile force is applied in the same plane as that of the pivot axis of the swivel joint and of the axes of the inlet and outlet to the swivel joint, the reaction to that force can only be resisted by the interconnecting members of the joint, and if the force is substantial a shearing of the elements may occur. In U.S. Pat. No. 4,791,961 of Nitzberg et al, a swivel-joint coupling is disclosed which substantially overcomes this problem by providing a two-axis swivel coupling having the longitudinal axis of the swivel joint and the end thereof connected to the flexible conduit offset relative to a plane parallel to one of the swivel axes and passing through the other so that the coupling could align the longitudinal axis of the end connected to the flexible conduit with the direction of any tensile force applied through the flexible conduit. The longitudinal axis at the connecting member with the flexible conduit is there disposed such that it is always offset from that plane which passes through the first swivel axis and is parallel to the second swivel axis.
Variations of these concepts are provided in Nitzberg et al U.S. Pat. No. 4,800,913 which provides a spherical swivel connector with detachable means, and Nitzberg et al U.S. Pat. No. 4,827,961 which provides a swivel-joint breakaway coupling having a passageway for maintaining laminer flow therethrough at high fuel flow rates. A swivel breakaway suitable for use with dual passage coaxial systems, i.e., those having a vapor return system for drawing off and returning the vapors to the storage tank while fuel is dispensed is disclosed in Nitzberg et al U.S. Pat. No. 4,827,960.
The self aligning features disclosed in the aforesaid Nitzberg et al U.S. Pat. No. 4,791,961 properly disconnects by permitting alignment of the end connected to the flexible conduit with the direction in which the tensile force is applied, but until such alignment occurs the interconnecting members resist the load so that the interaction of the forces on the interconnecting members results in wear. This problem is addressed in Nitzberg copending U.S. application Ser. No. 517,909 filed May 2, 1990, which provides a containment member for resisting the bending loads resulting from the tensile force before alignment occurs. Additionally, when breakaway swivel couplings of this type are not mounted at the preferred location adjacent to the nozzle, but is mounted to the rigid piping at the dispenser with the hose hanging therefrom not only does wear increase at the points of flexture, e.g., the mortise and tenon interconnecting members, but because of the weight of the hose acting on the coupling, an additional frictional resistance to self alignment results which may not only increase wear on the elements, but prevent self alignment to the tensile forces thereby retarding or even preventing uncoupling. This potential problem is intensified when the fuel dispensing system includes vapor recovery so that there is a coaxial assembly. The weight and lack of rigidity of coaxial vapor recovery hoses which have very soft and pliable outer conduit structures, and increased fluid seals and size, may not always result in self alignment of the coupling to tensile forces when mounted at a high position adjacent the fuel dispenser cabinet with the hose hanging therefrom. However, because of air pollution concerns, many states and local governments have mandated such vapor recovery systems.
Fire codes and other regulations presently adopted in regard to gasoline fuels mandate the use of a safety disconnect somewhere in the hose assemblies. As these codes are adopted in those areas requiring vapor recovery systems another problem evolves. The addition of the disconnect can add up to one foot to the overall length of the supply line from the dispenser to the nozzle, and even in the case of the apparatus disclosed in the aforesaid U.S. Pat. No. 4,827,960, in its extended position adds five inches to the overall assembly length. Because of this the hose can engage the ground adjacent the dispenser when the nozzle is returned to the dispenser. Regulations, however, provide that the total length of the hose assembly cannot permit the hose to contact the cement ground surface in the inoperative position since the hose would then wear out rapidly, a problem which is obviously significant from a safety standpoint with the soft outer surface coaxial hose assemblies. Since presently the hoses are manufactured in a standard size, modification of the hose size to accommodate the additional length resulting from the utilization of the coupling device, would add additional cost to the system.